In the American Society of Mechanical Engineers paper 72-WA/RT-10 titled "The Effect of Wheel Diameter on Tread Temperature in Grade Operation" by G. M. Cabble, it is shown that as the brake horsepower per railway vehicle wheel is increased, the temperature rise of the wheel is increased, given the same time. During a brake application, the mechanical energy of the brake horsepower applied to the wheel is converted to heat energy which is stored in and dissipated from the mass that constitutes the rotating wheel. Therefore, it is apparent that an increase in the mass of the wheel, and thus a corresponding increase in its heat sink capability, would effect a reduction in the maximum temperature attained by the wheel for a given brake horsepower applied thereto during a brake application.
Accordingly, it is the general purpose of this invention to provide a novel brake apparatus wherein the mass, and therefore, the heat sink, of a railway vehicle wheel is increased by securing a brake drum to the side of the wheel, or the axle on which the wheel is mounted, and applying a braking force from a movable member to the braking surfaces constituted by the peripheries of both the wheel and the drum via a multibrake shoe means that comprises a plurality of brake shoes between each pair of which and the movable member there is interposed a mechanism that includes either a lever pivoted intermediate its ends on the movable member with its ends in abutting relationship with the corresponding pair of brake shoes or a plurality of encased spherical members whereby, upon movement of the movable member in the direction of the wheel and brake drum, these brake shoes transmit substantially equal braking forces to the peripheral braking surfaces on the wheel and drum notwithstanding the rate of wear of one brake shoe exceeding that of the other.